Limit stop for aircraft gun mount training mechanisms



Jan. 2, 1951 F. c. EASTMAN 2,536,358

LIMIT STOP FOR AIRCRAFT GUN MOUNT TRAINING MECHANISMS Filed May 10, 19485 Sheets-Sheet l Jwen for: Fred C. Eds/man Jan. 2, 1951 F. c. EASTMANLIMIT STOP FOR AIRCRAFT GUN MOUNT TRAINING MECHANISMS 5 Sheets-Sheet 2Filed May 10, 1948 Jan. 2, 1951 F c EASTMAN 2,536,358

LIMI'f S'IOP FOR AIRCRAFT GUN MOUNT TRAINING MECHANISMS Filed May 10,1948 5 Sheets-Sheet 5 6 06 nven for:

Jan. 2, 1951 F. c. EASTMAN 2,536,358

LIMIT STOP FOR AIRCRAFT GUN MOUNT TRAINING MECHANISMS Filed May 10, 19485 Sheets-Sheet 4 jnventor' Wed C. Easfman 5 MS Am- A FMHUHH 1 1 ,r TH- Jww Ev Q% mm N 5 R IHHIHWMMIWWM I w F. C. EASTMAN LIMIT STOP FOR AIRCRAFTGUN MOUNT TRAINING MECHANISMS Jan. 2, 1951 5 Sheets-Sheet 5 Filed May10, 1948 nvnfor: Fred C. Easfmcm his Mo/"r7 iatented Jan. 2, 1951 LIMITSTOP FOR AIRCRAFT GUN MOUNT TRAINING MECHANISMS Fred C. Eastman,Marblehead, Mass., assignor to United Shoe Machinery Corporation,Flemington, N. J., a corporation of New York Application May 10, 1948,Serial No. 26,116

Claims- (CI. 89-41) This invention relates to the automatic remotecontrol of guns which are to be fired from an airplane and it is hereinillustrated as applied to guns contained Within an articulated fairingdesigned to project rearwardly from the fuselage.

It is well understood that means must be provided for limiting theextent of movement of the guns as they swing in azimuth and elevation soas to avoid damaging the structure of adjacent parts of the plane bycollision and also to keep the line of fire out of range of adjacentstructures on the plane. These means have previously been arranged tolimit the swinging movements toa pyramidal space.

Accordingly, an object of the invention is to provide an improvedgun-laying arrangement especially designed for airplane use.

An important feature of the invention resides in an electric controlarrangement for limiting the movements of the gun in azimuth andelevation so that movements can take place within a prescribed cone offire which may, for example, permit elevation or depression 45 from aneutral axis and a corresponding movement in azimuth so that a 90 coneof fire is obtained.

These and other features of the invention will best be understood from aconsideration of the following specification, taken in connection withthe accompanying drawings, in which Fig. 1 is a side elevation of a gunsupport with an associated fairing shown in section;

Fig. 2 is'a transverse vertical section through a gun adaptor on theline IIII of Fig. 1;

Fig. 3 is a view similar to Fig. l but with the guns tilted upwardly;

Fig. 4 is an enlarged horizontal section, through the tip of thefairing, taken on the line IV -IV at the right end of Fig. .3

Fig. 5 is an angular view, on a larger scale, .of the parts embodied ina limit-stop mechanism;

Fig. 16 is a vertical section through the operating pin of thismechanism;

Fig. is a side elevation, partly in section, of an equilibratoroffsetting the tilting efiect of the weight of the overhung guns; and IFig. 8 is a circuit diagram illustratin the con nection of thelimit-stop switches to the electrical drive mechanism. A

The arrangement to be described is designed as a movable support forfour machine guns l0, mounted upon a two-part adaptor I2 (Fig. 2) sothat they may be pointed in any direction within a 190 cone of fire. Theguns are surrounded by a suitable three section-,- articulated sheath orI within bearing 48 and 56.

fairing which preserves the aero-dynamic contour of the airplane. Inthis fairing the inner section which, for convenience, will be called aball M (Fig. 1), comprises a zone through a sphere. Associated with thisis a member which Will be called a ring l6 and a bullet-shaped pointportion l8 hereinafter called the point, which is provided with a tipl9. Openings (not shown) in the point are alined with the guns. The ringis provided with an inner edge member 20, the inner surface of which isspherical so that it may slide on the outer surface of the ball [4. Theouter end of the ring is provided with a similar internal member 22, theexposed surface of which is spherical to coact with a spherical endportion 24 on the point I8, the latter being urged inwardly against thering by a hydraulic mechanism to be later described.

The ball is made up of an inner ring 26 and an outer ring 28 joined by asheet-metal, frustoconical portion 38 as Well as by an outer sphericalportion 32. The inner ring is bolted to a ringlike channel 34 securedinside a corresponding circular opening in the airplane wall 35.

The gun mount is supported at the top by a bracket 36 attached to theouter ring 28 of the ball and at the bottom by a fixed gear segment 38on top of a limit switch casing 40 which is carried on top of asupporting bracket 42 which extends between the inner and outer rings26, 28.

Pivoted for movement about a substantially vertical axis 44 is a guncolumn 36 in the form of an irregularly shaped casting which is suppliedwith upper and lower pivot pins received The upper bearing 38 comprisesreversely arranged conical rolls to take the thrust of the column eitherup or down. This bearing 48 is carried by the bracket 36 while the lowerbearing 58 which serves as a pivot is carried on the gear segment 38.Rotation imparted to a pinion 52 engaging the teeth 54 on the gearsegment 38 swings this column about its axis 44 to obtain movements ofthe guns in azimuth and. the power for this swinging movement isobtained from a direct current motor 56 mounted on the column and whichis connected by reducing gears to the pinion 52.

The gun adaptor i2 is pivoted on the gun column on a horizontal axis 653to provide movements in elevation and has a gear segment 52 centered onthe axis so that changes in elevation may be effected by an electricmotor 54 supported on the column 46 and connected by reduction gears(not shown) to a pinion 66 which meshes with the teeth of the gearsegment 62.

It will be noted from Fig. 2 that the gun adaptor is provided withchutes $8 and it! which are directly above a passageway i2 provided atthe bottom of the bullet-shaped point i8, thus permitting disposal ofcartridge casings, belt links and the like. A camera I4 is supported ona bracket attached to the forward end of the adaptor and is pointed atthe target through openings I6 and I8.

To compensate for the obvious unbalance of the adaptor assembly I2 andthe guns IS, an equilibrator has been provided which comprises acylinder 85 pivotally connected at its right end at the point ifiil tobrackets 82 (Fig. 7) upon the gun adaptor. The equilibrator is providedwith a piston 84 having a piston rod 86 joined to a yoke 83 pivoted atas to the gun column 46. Oil 602 under pressure from an accumulator 92is delivered through a pipe Q (Fig. 1) to the cylinder portion 86 whichlies at one side of the piston 84. The accumulator 92 is supported in aring-like bracket 98 pivoted to the brackets 82 on the adaptor. withinthe accumulator 92 is maintained by providing air pressure through aflexible pipe I534 to one side of a flexible diaphragm Hi3 within theaccumulator. The pipe 24 is joined to an air storage tank I08 which issupplied from a motor driven compressor Ilil. It will be understood thatthe hydraulic system operating from the accumulator 92 to the cylinderas renders it easy to avoid creep. At the same time it is possible tomaintain exactly the desired pressure in the accumulator 92 bymaintaining a suitable air pressure against the diaphragm I436. As thegun is moved down, the pressure increases in the area fit but the leverarm between the center 65 and the cylinder axis decreases, thus leavingthe torque substantially constant.

When the guns are pointed at an extreme angle, the change in relationbetween the point I8 and the base of the ball I4 effects a change in thestraight line distance between the center of the ball I4, for example,and the tip of the point. Some yieldable arrangement must, therefore, beprovided for holding the point I8 in contact with the ring It andconsequently holding the ring it against the ball I4. It was found toothat the friction between these fairing parts, at or near the positionsof considerable angular displacement, was very much increased by anyordinary spring arrangement which might be devised for holding themtogether and this change was sufiicient to greatly increase the loadupon the motors 55 and 64 which produce the change in displacement.

Accordingly, a hydraulic system has been provided for holding the pointI8 inwardly against the ring I6 and this system includes a hydrauliccylinder I I2 which is slidable within an inner tube H4 clamped at IIGto the outer end of the adaptor I2 while the cylinder is attached to thepoint I3. Surrounding the tube H4 is an outer tube IIB which is slidableon the inner tube and the outer end of which is fastened to a crosspartition I28 in the point I8. On this cross partition I 20, areforwardly extending brackets I2! ,(Fig. 4) holding a pin I22 on whichthe tip I9 is tiltably secured by means of parallel ribs 523. Rigidlysecured to the ribs I23, is a hook I24 (Fig. 3) adapted to engage across pin I25 which is secured to the end of the cylinder H2 and thishook may be disengaged by tilting the tip.

The pressure upon the oil E82 Accidental tilting of the tip I9 isprevented by the end of a stub arm on a retaining latch E26 pivotedbetween ears extending rearwardly from the ribs I23 and connected by alink I2'I to a push button I28 at the end of the tip. When it is desiredto remove the point I8 of the fairing the button I28 is pushed inwardlyagainst a coil spring thus moving the stub arm aside and permitting thetip 59 to be tilted around its pivot I22 so as to drop the hook I24 fromthe cross pin #25 at the end of the cylinder. The point I8 and its capIt may then be withdrawn axially, with the outer tube I I8 sliding onthe inner tube I I4. When the button is not depressed, its spring urgesthe latch I26 clockwise, as viewed in Fig. 3, to a position determinedby contact of a long arm, on the latch, with the pin I22, thus holdingthe end of the stub arm over the cross pin I25 and preventing tilting ofthe tip I9.

Within the cylinder IE2 is a piston 43%) connected by a cross pin I32 tothe inner tube H4 and hence to the adaptor. Fluid under pressure fillsthe space between the piston and the left end of the cylinder. As thepoint portion I8 moves outward with respect to the inner tube M4 thespace between the piston I30 and the cylinder heads decreases thusincreasing the pressure acting to hold portion I8 inward and increasingthe friction between portion I8 and the ring I6 and between the ring andthe ball I4 with a resulting heavy load on the driving motors as the gunis trained. To avoid this the cylinder H2 is connected by pipes I34 andI36 to a cylinder E38 which is mounted on the adaptor I2 and to acylinder I40 (Fig. 3) which is mounted on the gun column 46. Each ofthese cylinders has a piston having an attached roller which rides, inthe first instance, against a cam I42 fixed on the gun column 46 and inthe second instance, against a cam I44 attached to the gear segment 38which is mounted on the fixed bracket 42 attached to the plane. By meansof this arrangement the pressure within the cylinder I38 and hence incylinder II2 is held at the desired maximum as the guns are pointedstraight to the rear and is decreased as the guns are elevated ordepressed, this following from the shape of the cam I42. A similar shapeof the cam I44 causes the pressure to be maximum within the cylinder Hitand hence in cylinder IIZ when the guns are pointed directly to the rearand decreases this effect as the guns are swung to one side or theother. Consequently, the pressure in the hydraulic system is relieved asthe guns and the portion I8 are swung away from center 3!! as tomaintain a free turning engagement between the point I8 and the ring andbetween the ring and the ball.

Any suitable system may be employed for the remote control of the motors56 and 64 so that the guns may be laid or directed at the target inaccordance with the wishes of a gunner who operates a sight (not shown)capable of being swung in azimuth and tilted in elevation. Thearrangement shown is electrical and alternating current signalscorresponding to the movements of the sight are produced by fourself-synchronous generators driven thereby, some of which areelectrically connected to two similar selfsynchronous transformers I50and I52 which are concerned with movements in azimuth while the othersare connected to a similar pair (not shown) which are concerned withmovements in elevation. These signals resulting from a lack ofcorrespondence between the position of the itcdatd signt fand thepositicn cf the guns, are transfiiitted by leads I53 through anamplifier I54 (Fig. 8) by which the alternating current signals areamplified and transformed to direct current and are transmitted from theterminals I56 and I58 on this amplifier to the opposite control fields16D and I62 of" an armature 'excited, dynamoelectric machine which isdriven by a motor I66. The mid point of these fields is grounded on amid point of the output of the amplifier I54. This machine acts as agenerator whose polarity and Voltage output is readily controlled and isfrequently designated by the trade name Amplisync. These control fieldsI66 and I62 are along represented by brushes which are com nettedthrough a series compensatin field windin"! 168 to the driving 'motor64-. The flux along this central axis is in quadrature with the fluxalehg ah misrepresented by other brushes which are short circui'ted. Therespective control fields I68 and I62 o pose each other and theresultant depends u on the direction and amplitude of the currentdelivered from the amplifier I54. This dynamo-electric machine 464delivers current at a Varying voltage to the motor 64 to drive it at avarying speed depending upon the divergence between the sight and theguns in elevation and it will be understood that when theself-synchronous transformers '(not shown.) which are responsive titmovements in elevation, indicate a position of correspondence betweenthe sight and the guns then the control fields I60 and I62 balance outand no further current is delivered by the amplid-yne generator I64 andthe motor 64 stops.

It will be understood that two separate sets of self-synchronousgenerators and transformers such as have just been described areemployed, one for movements in az muth and one for movements inelevation and that each of these sets is provided with an amplifier fordelivering current to the control field windings of an Amplidynegenerator. Only one such arrangement is illus-- trated in Fig. 8 whichis the one controlling movements in elevation. The use of twoself-synchronous generators and two self-synchronous transformers on thesight and on the gun drive respectively is Well understood and makes forgreater accuracy and smoothness in operation. These machine at the sightare connected by gears in a ratio of 31 to 1 as are the similartransformers such as those shown at I50, I52 on the column 46. Thetransformer devices are also geared to the drive terminating in thepinion 52 so that the 1 -1 self-synchronous transformer I50 moves in adirect ratio with the azimuth movements of the gun column while thecoacting transformer I52 moves in a prime ratio of 31 to '1 with respectthereto.

The foregoing explanation has been included for the sake of facilitatingan explanation of the limit-stop switch mechanism of Figs. '5 and 6 bymeans of which the movements of the gun are restricted to the largestcone of fire which is permitted by the range of movement mechanicallypossible for the articulated fairing comprising the ball I4, the ring itand the point I8. It will be understood that when limit switches areemployed outside the gun mount or in some such location 'as are thephysical limit stops shown in Letters Patent of the United States2,391,956 granted January 1, 1946, upon my application, then the areadefined is a pyramid, the largest angle at the apex of which isrepresented by the angle between "diagonally opposite corner lines ofthe "pyramid. With the arrangement he-rem shown, however, and which isnow to be described, it is possible to employ the additional spacebetween such a pyramid and a cone of fire which is inscribed to includethe corners of the pyramid.

To this end, a centrally located mechanism shown in Figs. 5 and 6 isemployed to cause movements of the adaptor I2 in elevation and inazimuth to operate a series of limit switches I12, I14, I16 and I18which are arranged to break the connections between the amplifiers andthe control fields so as to stop further movement in any desireddirection. The movements of the gun produce corresponding movements of apin I which is mounted in and is held normally vertical with respect toa plate I82 but which may tilt with respect thereto upon yieldin of aspring I84 in order to avoid damage to the mechanism. To producerepresentative movements of this pin I80, the plate 182 is slidable in acarrier 1-86 having a clearance opening I81 for the pin. This carrier inturn is mounted for sliding movement, laterally or at right angles tothe direction of sliding movement of the plate, by supporting it on atube I88 which is fixed in the casing 433 (Fig. 1) in which thismechanism is mounted and in a groove I89 in said casing.

Movements of the slide I82 in its carrier I86 to represent changes inelevation are 'efiected by a post I90 which is rigidly mounted on theslide and is physically operated by means of a cam I92 which is mountedon the gun adaptor I2 and which is designed with a constant increment sothat inches of movement of the slide 482 for example, equal to apredetermined number of -degrees of angular movement of the gun. Thiscam I92 engages a roll 494 on the end of an arm I96 attached to a pin I98 which is journaled in the gun column 46 and which also carries an arm200 bearing on the upper end of a rod 292 connected through a two partbell crank 284, 255 and a connecting rod 206 with the post 59. Ballconnections are employed to insure freedom of movements. The bell crankpart 205 is slotted to pass a clamp screw 208 threaded in the part 284thereby to provide for a setting-up adjustment. The bell crank part 205is pinned to a pivot tube 209 journaled in brackets 2 !0 attached to theoutside of the casing 48. A coil spring 244 between one bracket and ablock 2 I3 clamped on the end of the pivot tube 209 serves to hold theroll I94 against its cam I92.

In order that the movements of the pin 18-?! may also reflect movementsof the gun in azimuth, a tube 2I2 joined 'to the gun -col-umn4 6 isprovided with a gear segment 2 clamped on the tube and capable ofsetting-up adjustment thereon. The segment 21-4 transmits motion to thecarrier I86 by means ofopposed integral segments 2I6 which mesh with thesegment 2M and with teeth 2I8 on the carrier I86. The pin I89, providedwith a rubber collar 220, moves within the opening 2'22 of a hollow,ring-like template 224.

This template is connected by a bell crank 226 pivoted on the controlbox and by a link to a switch arm 228 swingably mounted on a fixed axisin the control box and having terminal screws'coacting with theoperating buttons of microswitches I12 and [14. The template 224 is alsoconnected by a link 230 to another similarly mounted switch arm 232which is arranged to operate the microswitches I16 and I-18. The opening222 of the template which is swung between these switch arms is designedso as to give the desired cone of fire in accordance with the dimensionsof the gun mount and the fairing associated with it and the ordinatesand abscissae of the position of the pin I80 define correspondingpositions of the guns in space.

The way in which the limit switches H2 to I18 are included in thecircuits of the control fields I60 and I62 of the amplidyne generator isbest shown in Fig. 8 where the switch I16 which determines the limit ofdepression of the gunand the switch I78 which determines the limit ofelevation of the gun are shown.

, To effect the desired result these mechanically operated switches areeach included in circuit with a pair of relays. Thus the switch I18 isin series with the coils of a field relay 280 and a limit relay 282.These relays are normally energized from a direct current supply circuit284 from which they receive power whenever the apparatus has been put inoperating condition. Similarly the limit switch I18 controls the coilsof a field relay 286 and a limit relay 288. The contacts 290 and 292 ofthe limit relays are in series with one another and with the coil 2% ofa brake solenoid which, when it is energized as it is in normaloperation, relieves the pressure of a brake arm which is normally drawnagainst the brake by a spring 298. The field relay 289 has a pair 300 ofupper contactors and a pair 302 of lower contactors and the field relay286 is similarly arranged.

In the operating conditions which are shown in Fig. 3, these field relaycontacts in their upper position serve to connect the terminals of thecontrol field windings I60 and IE2 of the Amplidyne" to the terminalsI56 and I58 of the signal amplifier I54. The lower contact bars of eachpair 300 and 392 control the circuits from the signal amplifierterminals to the opposed coils 304 and 306 of a back-out relay 3H Themid point between these coils is joined to the negative side of thesupply circuit 28d. The contact bars of this back-out relay are normallyheld in an open position by a spring 3 I2.

It will be understood that the breaking of the circuit by the limitswitch such as that at I18 will have been caused by a movement of thesight by the gunner to a position calling for movement of the gun beyondits desired range and if this position of the sight is maintained afterthe limit switch has been opened then the current to the back-out relaywill be in such a direction that the resultant field in the solenoid ofthe latter is ineffective to close the contacts thereof. If, however thegunner moves the sight to a position within the prescribed cone of firethen the backout relay will close, permitting the guns to. be backed outof their abnormal position. The clos ing of the lower sets of contactsof the back-out relay 3Ill will connect the signal amplifier terminalsto the terminals of the control fields I50 and I62 while its uppercontacts will close a circuit to energize the brake solenoid 294 so asto lift the brake arm 296 to the position shown and operation of thesystem may then proceed in normal fashion for the reason that thepressure upon the limit switch I76 will be relieved by the withdrawal ofthe guns, permitting that switch to close a circuit to energize thefield relay 2% to reestablish the normal circuits to the control fieldsand also deenergizing the back-out relay 3I0. At the same time the limitrelay 282 will be reenergized thus reestablishing the circuit to thebrake solenoid 284.

Inasmuch as the control which is illustrated in Fig. 8 is duplicated forcontrol of movements in azimuth it will be seen that the guns maybe laidautomatically by remote control, being balanced by the equilibrator 80.Although no mention has been made of the firing circuits since thatforms no part of the invention, these will be understood to becontrolled from the sight and preferably will be provided withinterrupter means operative when the guns move beyond the limit cone offire which is prescribed by the limit switches I72 to I78. During thesemovements of the gun the pressure which holds together the parts I4, I6and I8 of the articulated fairing will .be automatically controlled soas to prevent the air stream from separating these parts by reason ofany undue slackening of the pressure required to hold the parts togetherand at the same time sufiicient pressure will always be maintainedwithin the cylinder II2 to hold them together but without causing anyundue friction. The feeding of ammunition to the guns can be car-- riedout automatically by means of any wellknown system which delivers thecartridges automatically from a storage receptacle inside the planeitself and allows the links of the conveyor chain as well as thecartridge casings and anyduds to fall out through the chute TI. 7

Features of the invention relating to the articulated fairings are notclaimed herein since theyare included in a divisional application SerialNo. 77,810, filed February 23, 1949, in my name, and patented November21, 1950, as Patent No. 2,530,571.

Having thus described my invention, what I- claim as new and desire tosecure by Letters Patent of the United States is:

1. A limit stop for controlling the limit of movement of a gun supportedfor swinging movement and having a gun laying means, said limit stopcomprising control devices for stopping the movement imparted by saidlaying means when the limit is reached, means for operating said controldevices, and means for moving said operating means comprising a hollowring-like template connected to the moving means and a memher within thehollow template arranged for.

movement in a plurality of directions to an extent proportionate to themovements of the gun in corresponding directions to move said template.

2. In a limit stop for a gun supported for swinging movement and havingmeans for moving the gun to point it in the desired direction, controldevices for stopping said gun moving means at predetermined boundaries,and means for operating said control devices comprising a swinging arm,a hollow template connected to said arm and pivotally supported formovement toward and away from the arm, a pin within and arranged toswing said template, and means' connected to the gun for moving said pinin a direction and to an extent corresponding to the movement of thegun.

3. In a limit stop for a gun supported for movements by power means inelevation and in azimuth, a plurality of switches for controlling saidpower means, arms for operating said switches, a hollow template swungbetween said arms and a, pin projecting through said template, said pinbeing mounted for movement in a plurality of. directions, and means forconnecting the pin to the gun thereby to impart movements to the pincorresponding to the movements of the gun to. move the template when thelimit is reached.

4. In a limit stop for a gun supported for movement by power means in aplurality of directions,

a pluralityoi control devices {or limiting the action of said powermeans in f our directions, a slide mounted for movement i'n fourdirections, means for. imparting movements thereto corresponding tomovements of the gun, a pin on said slide, a template surrounding saidpin and movable there y, and means for connecting said template to'sa dcontrol devices. i

5. In ajlimit stop for a gun supported for movement by electrical meansto and fro both in azimuth an elevation, switches connected to limit theextent of movement imparted to the gun by said electrical means in anyone of the four directions, swinging arms for oper ing said switches, atemplate linked to said arrn 'fa. pin movable in four directionscorrespondinggto the movements of the gun and positioned Ito contactwith and to move said template thereby to operate the switches-2 FRED c.EASTMAN.

REFERENCES CITED The following referencesare of record in the file ofthis patent:

Number Number 10 UNITED STATES PATENTS Name Date Ryan Dec. 15, 1908Joyce July 3, 1923 Joyce July 3, 1923 Muller Aug. 25, 1931 Mittag et alMay 8, 1934 Morris Apr. 9, 1940 Sanders May 7, 1940 Kamenarovic July 1,1941 Caminez Apr. 7, 1942 Zerangue Feb. 29, 1944 Lesnlck May 16, 1944Edwards et a1 Aug. 22, 1944 Walle et al June 19, 1945 Reiniger Sept. 10,1 946 Soenke Sept. 24, 1946 Trotter Oct. 15, 1946 Joy et a1 1 May 20,1947 Watkins et a1 Jan. 20, 1948 Villepigue Apr. 20, 1948 HarringtonOct. 5, 1948 FOREIGN PATENTS Country Date France July 26, 1902

